Mobile wireless communication devices, such as a cellular telephone or a wireless personal digital assistant, can provide a wide variety of communication services including, for example, voice communication, text messaging, internet browsing, and electronic mail. Mobile wireless communication devices can operate in a wireless communication network of overlapping “cell areas”, each cell area providing a geographic area of wireless signal coverage that extends from a radio frequency access network system located in (or at the edge of) the cell area. The radio frequency access network system can include a base transceiver station (BTS) in a Global System for Communications (GSM) network or a Node B in a Universal Mobile Telecommunications System (UMTS) network. The radio frequency access network system can also include a radio access network (RAN) in a Code Division Multiple Access 2000 (CDMA2000) network. The term “cell area” can be referred to as a “cell” for a UMTS network and as a “sector” for a GSM network or a CDMA2000 network. To simplify terminology and maintain consistency herein, we describe a mobile wireless communication device as connected to a “cell” when the mobile wireless communication device is connected to at least part of a radio frequency access network system that covers a geographic area. Signals for multiple cells can overlap at a given geographic location, and a mobile wireless communication device can connect to one or more cells in a wireless communication network.
The mobile wireless communication device can receive signals transmitted from one or more cells in the wireless communication network. The radio frequency access network systems in each of the cell areas can be located at different distances from the mobile wireless communication device, and therefore signals received at the mobile wireless communication device in a downlink direction can vary in signal strength and/or signal quality. Similarly signals from the mobile wireless communication device received by the radio network access systems in an uplink direction can vary in signal strength and/or signal quality. The mobile wireless communication device and the radio network access systems can measure and monitor their respectively received signals to determine to which cells a connection can be achieved and maintained. Together with one or more radio network access systems in the wireless communication network, the mobile wireless communication device can select to which cells to connect and disconnect and what transmit power level to use as the mobile wireless communication device moves throughout the wireless network.
The wireless network can provide several different services based on different generations of communication protocols at the same time to ensure backward compatibility between newer and older devices. Different cells within a wireless network can also be upgraded selectively as the wireless network evolves, and therefore not all cells can offer the same capability to the mobile wireless communication device. Advanced mobile wireless communication devices can support multiple service connections simultaneously to different cells, and one service connection can use a different generation communication protocol than another service connection to a separate cell operating at the same time. When connected to multiple cells, the mobile wireless communication device can receive transmit power control commands from one or more of the multiple cells to which it is connected. The transmit power control commands can regulate the mobile wireless communication device's transmit power levels. Some services, such as high speed data services, can require higher transmit power levels than lower speed voice or data services. The transmit power level for the mobile wireless communication device, however, can be set to a lower transmit power level by a radio network subsystem in a cell to which the mobile wireless communication device can be connected for lower speed voice or data service. The lower transmit power level can be adequate for the lower speed voice or data service; however, the lower transmit power level can interfere with the capability of the mobile wireless communication device to transmit to a different cell for a simultaneous high speed data connection.
Thus there exists a need to controlling transmit power levels used for communication between a mobile wireless communication device and multiple cells in a wireless communication network more effectively.